Psychometric properties of the Strength and Difficulties Questionnaire from five European countries.

The Strength and Difficulties Questionnaire (SDQ) is a brief screening instrument for assessing emotional and behavioural problems in children and adolescents. This study examined the factor structure and validity of the self-report original English version of the SDQ and four of its many translations (German, Cypriot Greek, Swedish, and Italian). A total of 2418 adolescents from five European countries (Germany, Cyprus, England, Sweden, Italy), ages 12 to 17 years, participated. The sample was drawn from general (school) populations. In addition to the SDQ, all participants completed the Spence Children's Anxiety Scale (SCAS), a measure of anxiety symptoms. The internal consistency and validity of the SDQ total difficulties were good for most countries. Confirmatory factor analysis showed that both five- and three-factor models provided good fit for the whole sample; however, the three-factor model fit somewhat better than the five-factor model. The factor structure differed across countries, with the three-factor model showing better fit indices in Cyprus, whereas the five-factor model fitted better in Germany. Fit indices for the UK, Sweden, and Italy were poor for both models. When the reversed items were removed, the goodness-of-fit improved significantly for the total sample and in each country. It is therefore recommended that the reversed items be removed or re-worded in future studies.